Change default line-height of fs-header(3) from 28px to 24px

As discussed with the design team, this changes the default line-height of `fs-header(3)` to be 24px from 28px.

- Change line-height
- Bump version number

I also did the due-diligence in Frontend and grepped the code base with @paulrobertlloyd for references, all of which were used for very similar component headings.

/cc @kaelig